A variety of methods and compositions of biomaterials have been used to repair or regenerate bone loss due to either trauma or disease. The term osteogenic commonly refers to substances which are osteoconductive and/or osteoinductive.
Conventional implantable bone repair materials provided a matrix or scaffolding for migration into, proliferation and subsequent differentiation of cells responsible for osteogenesis (Nashef U.S. Pat. No. 4,678,470). While the compositions provided by this approach provided a stable structure for invasive bone growth, they did not promote bone cell proliferation or bone regeneration. Generally, these materials are referred to as osteoconductive.
Subsequent approaches have used bone repair matrices containing bioactive proteins which when implanted into a bone defect provided not only a scaffolding for invasive bone ingrowth, but active induction of bone cell replication and differentiation. These materials are generally referred to as osteoinductive.
In general, osteoinductive compositions comprised a matrix which provided the scaffolding for invasive growth of the bone, anchorage dependent cells, and an osteoinductive protein source. The matrix may be a variety of materials, such as: collagen (Jefferies U.S. Pat. Nos. 4,394,370 and 4,472,840); inorganically based materials, such as a biodegradable porous ceramic (Urist U.S. Pat. No. 4,596,574); or, polylactic acid (Urist U.S. Pat. No. 4,563,489).
Osteogenic compositions and methods for making the same are described in Jefferies U.S. Pat. Nos. 4,394,370 and 4,472,840. Jefferies describes complexes of reconstituted collagen and demineralized bone particles or complexes of reconstituted collagen and a solubilized bone morphogenetic protein, fabricated into a sponge suitable for in vivo implantation into osseus defects. Structural durability of these compositions may be enhanced by crosslinking with glutaraldehyde.
In particular, two specific substances have a well established ability to induce the formation of new bone (i.e., to be osteoinductive) through the process of osteogenesis:
demineralized bone particles or powder, and bone morphogenetic proteins (BMPs) (Urist U.S. Pat. Nos. 4,595,574, 4,563,489, 4,551,256). A variety of other bone inducing factors have been characterized as well (Seydin et al., U.S. Pat. No. 4,627,982).
While a wide variety of osteoinductive compositions have been used in bone repair and regeneration there is always need in the art for improvements or enhancements of existing technologies which would accelerate and enhance bone repair and regeneration allowing for a faster recovery for the patient receiving the osteogenic implants.